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Materials: Engineering, Science, Processing and Design
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Materials
Engineering, Science,
Processing and Design
Michael Ashby, Hugh Shercliff and David Cebon
University of Cambridge,
UK
AMSTERDAM • BOSTON • HEIDELBERG • LONDON • NEW YORK • OXFORD
PARIS • SAN DIEGO • SAN FRANCISCO • SINGAPORE • SYDNEY • TOKYO
Butterworth-Heinemann is an imprint of Elsevier
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Butterworth-Heinemann is an imprint of Elsevier
Linacre House, Jordan Hill, Oxford OX2 8DP
30 Corporate Drive, Suite 400, Burlington, MA 01803
First edition 2007
Copyright © 2007, Michael Ashby, Hugh Shercliff and David Cebon. Published by Elsevier Ltd.
All rights reserved.
The right of Michael Ashby, Hugh Shercliff and David Cebon to be identified as the authors of this work has been
asserted in accordance with the Copyright, Designs and Patents Act 1988
No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form
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Notice
No responsibility is assumed by the publisher for any injury and/or damage to persons or property
as a matter of products liability, negligence or otherwise, or from any use or operation of any methods,
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British Library Cataloguing in Publication Data
A catalogue record for this book is available from the British Library
Library of Congress Cataloging-in-Publication Data
A catalog record for this book is available from the Library of Congress
ISBN-13: 978-0-7506-8391-3
ISBN-10: 0-7506-8391-0
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visit our web site at http://books.elsevier.com
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07 08 09 10 10 9 8 7 6 5 4 3 2 1
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Contents
Preface ix
Acknowledgements xi
Resources that accompany this book xii
Chapter 1 Introduction: materials—history and character 1
1.1 Materials, processes and choice 2
1.2 Material properties 4
1.3 Design-limiting properties 9
1.4 Summary and conclusions 10
1.5 Further reading 10
1.6 Exercises 10
Chapter 2 Family trees: organizing materials and processes 13
2.1 Introduction and synopsis 14
2.2 Getting materials organized: the materials tree 14
2.3 Organizing processes: the process tree 18
2.4 Process–property interaction 21
2.5 Material property charts 22
2.6 Computer-aided information management for materials and processes 24
2.7 Summary and conclusions 25
2.8 Further reading 26
2.9 Exercises 26
2.10 Exploring design using CES 28
2.11 Exploring the science with CES Elements 28
Chapter 3 Strategic thinking: matching material to design 29
3.1 Introduction and synopsis 30
3.2 The design process 30
3.3 Material and process information for design 34
3.4 The strategy: translation, screening, ranking and documentation 36
3.5 Examples of translation 39
3.6 Summary and conclusions 43
3.7 Further reading 43
3.8 Exercises 44
3.9 Exploring design using CES 46
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Chapter 4 Stiffness and weight: density and elastic moduli 47
4.1 Introduction and synopsis 48
4.2 Density, stress, strain and moduli 48
4.3 The big picture: material property charts 56
4.4 The science: what determines density and stiffness? 58
4.5 Manipulating the modulus and density 69
4.6 Summary and conclusions 73
4.7 Further reading 74
4.8 Exercises 74
4.9 Exploring design with CES 77
4.10 Exploring the science with CES Elements 78
Chapter 5 Flex, sag and wobble: stiffness-limited design 81
5.1 Introduction and synopsis 82
5.2 Standard solutions to elastic problems 82
5.3 Material indices for elastic design 89
5.4 Plotting limits and indices on charts 95
5.5 Case studies 99
5.6 Summary and conclusions 106
5.7 Further reading 107
5.8 Exercises 107
5.9 Exploring design with CES 109
5.10 Exploring the science with CES Elements 109
Chapter 6 Beyond elasticity: plasticity, yielding and ductility 111
6.1 Introduction and synopsis 112
6.2 Strength, plastic work and ductility: definition and measurement 112
6.3 The big picture: charts for yield strength 116
6.4 Drilling down: the origins of strength and ductility 118
6.5 Manipulating strength 127
6.6 Summary and conclusions 135
6.7 Further reading 136
6.8 Exercises 137
6.9 Exploring design with CES 138
6.10 Exploring the science with CES Elements 138
Chapter 7 Bend and crush: strength-limited design 141
7.1 Introduction and synopsis 142
7.2 Standard solutions to plastic problems 142
7.3 Material indices for yield-limited design 149
7.4 Case studies 154
7.5 Summary and conclusions 158
7.6 Further reading 159
iv Contents
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7.7 Exercises 159
7.8 Exploring design with CES 161
Chapter 8 Fracture and fracture toughness 163
8.1 Introduction and synopsis 164
8.2 Strength and toughness 164
8.3 The mechanics of fracture 166
8.4 Material property charts for toughness 172
8.5 Drilling down: the origins of toughness 174
8.6 Manipulating properties: the strength–toughness trade-off 178
8.7 Summary and conclusions 181
8.8 Further reading 181
8.9 Exercises 182
8.10 Exploring design with CES 183
8.11 Exploring the science with CES Elements 183
Chapter 9 Shake, rattle and roll: cyclic loading, damage and failure 185
9.1 Introduction and synopsis 186
9.2 Vibration and resonance: the damping coefficient 186
9.3 Fatigue 187
9.4 Charts for endurance limit 194
9.5 Drilling down: the origins of damping and fatigue 195
9.6 Manipulating resistance to fatigue 196
9.7 Summary and conclusions 198
9.8 Further reading 199
9.9 Exercises 199
9.10 Exploring design with CES 202
Chapter 10 Keeping it all together: fracture-limited design 203
10.1 Introduction and synopsis 204
10.2 Standard solutions to fracture problems 204
10.3 Material indices for fracture-safe design 205
10.4 Case studies 209
10.5 Summary and conclusions 220
10.6 Further reading 221
10.7 Exercises 221
10.8 Exploring design with CES 224
Chapter 11 Rub, slither and seize: friction and wear 227
11.1 Introduction and synopsis 228
11.2 Tribological properties 228
11.3 Charting friction and wear 229
11.4 The physics of friction and wear3 231
Contents v
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11.5 Design and selection: materials to manage friction and wear 235
11.6 Summary and conclusions 240
11.7 Further reading 241
11.8 Exercises 241
11.9 Exploring design with CES 243
Chapter 12 Agitated atoms: materials and heat 245
12.1 Introduction and synopsis 246
12.2 Thermal properties: definition and measurement 246
12.3 The big picture: thermal property charts 249
12.4 Drilling down: the physics of thermal properties 251
12.5 Manipulating thermal properties 257
12.6 Design to exploit thermal properties 258
12.7 Summary and conclusions 268
12.8 Further reading 269
12.9 Exercises 270
12.10 Exploring design with CES 271
12.11 Exploring the science with CES Elements 272
Chapter 13 Running hot: using materials at high temperatures 275
13.1 Introduction and synopsis 276
13.2 The temperature dependence of material properties 276
13.3 Charts for creep behavior 281
13.4 The science: diffusion and creep 284
13.5 Materials to resist creep 293
13.6 Design to cope with creep 296
13.7 Summary and conclusions 304
13.8 Further reading 305
13.9 Exercises 305
13.10 Exploring design with CES 308
13.11 Exploring the science with CES Elements 308
Chapter 14 Conductors, insulators and dielectrics 311
14.1 Introduction and synopsis 312
14.2 Conductors, insulators and dielectrics 313
14.3 Charts for electrical properties 317
14.4 Drilling down: the origins and manipulation of electrical properties 320
14.5 Design: using the electrical properties of materials 331
14.6 Summary and conclusions 338
14.7 Further reading 338
14.8 Exercises 339
14.9 Exploring design with CES 341
14.10 Exploring the science with CES Elements 343
vi Contents
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Chapter 15 Magnetic materials 345
15.1 Introduction and synopsis 346
15.2 Magnetic properties: definition and measurement 346
15.3 Charts for magnetic properties 351
15.4 Drilling down: the physics and manipulation of magnetic properties 353
15.5 Materials selection for magnetic design 358
15.6 Summary and conclusions 363
15.7 Further reading 363
15.8 Exercises 364
15.9 Exploring design with CES 365
15.10 Exploring the science with CES Elements 366
Chapter 16 Materials for optical devices 367
16.1 Introduction and synopsis 368
16.2 The interaction of materials and radiation 368
16.3 Charts for optical properties 373
16.4 Drilling down: the physics and manipulation of optical properties 375
16.5 Optical design 381
16.6 Summary and conclusions 382
16.7 Further reading 383
16.8 Exercises 383
16.9 Exploring design with CES 384
16.10 Exploring the science with CES Elements 385
Chapter 17 Durability: oxidation, corrosion and degradation 387
17.1 Introduction and synopsis 388
17.2 Oxidation, flammability and photo-degradation 388
17.3 Oxidation mechanisms 390
17.4 Making materials that resist oxidation 392
17.5 Corrosion: acids, alkalis, water and organic solvents 395
17.6 Drilling down: mechanisms of corrosion 396
17.7 Fighting corrosion 401
17.8 Summary and conclusions 404
17.9 Further reading 405
17.10 Exercises 405
17.11 Exploring design with CES 406
17.12 Exploring the science with CES Elements 407
Chapter 18 Heat, beat, stick and polish: manufacturing processes 409
18.1 Introduction and synopsis 410
18.2 Process selection in design 410
18.3 Process attributes: material compatibility 413
18.4 Shaping processes: attributes and origins 414
Contents vii
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18.5 Joining processes: attributes and origins 423
18.6 Surface treatment (finishing) processes: attributes and origins 426
18.7 Estimating cost for shaping processes 427
18.8 Computer-aided process selection 432
18.9 Case studies 434
18.10 Summary and conclusions 443
18.11 Further reading 444
18.12 Exercises 445
18.13 Exploring design with CES 446
18.14 Exploring the science with CES Elements 447
Chapter 19 Follow the recipe: processing and properties 449
19.1 Introduction and synopsis 450
19.2 Microstructure of materials 450
19.3 Microstructure evolution in processing 454
19.4 Processing for properties 462
19.5 Case studies 464
19.6 Making hybrid materials 472
19.7 Summary and conclusions 474
19.8 Further reading 475
19.9 Exercises 476
19.10 Exploring design with CES 477
Chapter 20 Materials, processes and the environment 479
20.1 Introduction and synopsis 480
20.2 Material consumption and its growth 480
20.3 The material life cycle and criteria for assessment 483
20.4 Definitions and measurement: embodied energy, process
energy and end of life potential 484
20.5 Charts for embodied energy 490
20.6 Design: selecting materials for eco-design 493
20.7 Summary and conclusions 497
20.8 Appendix: some useful quantities 498
20.9 Further reading 498
20.10 Exercises 499
20.11 Exploring design with CES 501
Index 503
viii Contents
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Preface
Science-led or Design-led? Two approaches to materials teaching
Most things can be approached in more than one way. In teaching this is especially true. The way
to teach a foreign language, for example, depends on the way the student wishes to use it—to read
the literature, say, or to find accommodation, order meals and buy beer. So it is with the teaching
of this subject.
The traditional approach to it starts with fundamentals: the electron, the atom, atomic bonding,
and packing, crystallography and crystal defects. Onto this is built alloy theory, the kinetics of
phase transformation and the development of microstructure on scales made visible by electron and
optical microscopes. This sets the stage for the understanding and control of properties at the millimeter or centimeter scale at which they are usually measured. The approach gives little emphasis
to the behavior of structures, methods for material selection, and design.
The other approach is design-led. The starting point is the need: the requirements that materials
must meet if they are to perform properly in a given design. To match materials to designs requires
a perspective of the range of properties they offer and the other information that will be needed about
them to enable successful selection. Once the importance of a property is established there is good
reason to ‘drill down’, so to speak, to examine the science that lies behind it—valuable because an
understanding of the fundamentals itself informs material choice and usage.
There is sense in both approaches. It depends on the way the student wishes to use the information.
If the intent is scientific research, the first is the logical way to go. If it is engineering design, the second makes better sense. This book follows the second.
What is different about this book?
There are many books about the science of engineering materials and many more about design.
What is different about this one?
First, a design-led approach specifically developed to guide material selection and manipulation.
The approach is systematic, leading from design requirements to a prescription for optimized material
choice. The approach is illustrated by numerous case studies. Practice in using it is provided by
Exercises.
Second, an emphasis on visual communication and a unique graphical presentation of material
properties as material property charts. These are a central feature of the approach, helpful both in
understanding the origins of properties, their manipulation and their fundamental limits, as well as
providing a tool for selection and for understanding the ways in which materials are used.
Third, its breadth. We aim here to present the properties of materials, their origins and the way
they enter engineering design. A glance at the Contents pages will show sections dealing with:
• Physical properties
• Mechanical characteristics
• Thermal behavior
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• Electrical, magnetic and optical response
• Durability
• Processing and the way it influences properties
• Environmental issues
Throughout we aim for a simple, straightforward presentation, developing the materials science as
far as is it helpful in guiding engineering design, avoiding detail where this does not contribute to
this end.
And fourth, synergy with the Cambridge Engineering Selector (CES)1—a powerful and widely
used PC-based software package that is both a source of material and process information and a
tool that implements the methods developed in this book. The book is self-contained: access to the
software is not a prerequisite for its use. Availability of the CES EduPack software suite enhances
the learning experience. It allows realistic selection studies that properly combine multiple constraints on material and processes attributes, and it enables the user to explore the ways in which
properties are manipulated.
The CES EduPack contains an additional tool to allow the science of materials to be explored in
more depth. The CES Elements database stores fundamental data for the physical, crystallographic,
mechanical, thermal, electrical, magnetic and optical properties of all 111 elements. It allows interrelationships between properties, developed in the text, to be explored in depth.
The approach is developed to a higher level in two further textbooks, the first relating to mechanical design2, the second to industrial design3.
x Preface
1 The CES EduPack 2007, Granta Design Ltd., Rustat House, 62 Clifton Court, Cambridge CB1 7EG, UK,
www.grantadesign.com.
2 Ashby, M.F. (2005), Materials Selection in Mechanical Design, 3rd edition, Butterworth-Heinemann, Oxford, UK,
Chapter 4. ISBN 0-7506-6168-2. (A more advanced text that develops the ideas presented here in greater depth.) 3 Ashby, M.F. and Johnson, K. (2002) Materials and Design—The Art and Science of Material Selection in Product
Design, Butterworth-Heinemann, Oxford, UK. ISBN 0-7506-5554-2. (Materials and processes from an aesthetic
point of view, emphasizing product design.)
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Acknowledgements
No book of this sort is possible without advice, constructive criticism and ideas from others. Numerous
colleagues have been generous with their time and thoughts. We would particularly like to recognize suggestions made by Professors Mick Brown, Archie Campbell, Dave Cardwell, Ken Wallace and
Ken Johnson, all of Cambridge University, and acknowledge their willingness to help. Equally valuable has been the contribution of the team at Granta Design, Cambridge, responsible for the development of the CES software that has been used to make the material property charts that are a
feature of this book.
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Resources that accompany this book
Exercises
Each chapter ends with exercises of three types: the first rely only on information, diagrams and
data contained in the book itself; the second makes use of the CES software in ways that use the
methods developed here, and the third explores the science more deeply using the CES Elements
database that is part of the CES system.
Instructor’s manual
The book itself contains a comprehensive set of exercises. Worked-out solutions to the exercises are
freely available to teachers and lecturers who adopt this book. To access this material online please
visit http://textbooks.elsevier.com and follow the instructions on screen.
Image Bank
The Image Bank provides adopting tutors and lecturers with jpegs and gifs of the figures from the
book that may be used in lecture slides and class presentations. To access this material please visit
http://textbooks.elsevier.com and follow the instructions on screen.
The CES EduPack
CES EduPack is the software-based package to accompany this book, developed by Michael Ashby
and Granta Design. Used together, Materials: Engineering, Science, Processing and Design and CES
EduPack provide a complete materials, manufacturing and design course. For further information
please see the last page of this book, or visit www.grantadesign.com.
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Chapter 1
Introduction: materials—
history and character
Chapter contents
1.1 Materials, processes and choice 2
1.2 Material properties 4
1.3 Design-limiting properties 9
1.4 Summary and conclusions 10
1.5 Further reading 10
1.6 Exercises 10
Professor James Stuart, the first Professor
of Engineering at Cambridge.
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2 Chapter 1 Introduction: materials—history and character
1.1 Materials, processes and choice
Engineers make things. They make them out of materials. The materials have
to support loads, to insulate or conduct heat and electricity, to accept or reject
magnetic flux, to transmit or reflect light, to survive in often-hostile surroundings, and to do all this without damage to the environment or costing
too much.
And there is the partner in all this. To make something out of a material you
also need a process. Not just any process—the one you choose has to be compatible with the material you plan to use. Sometimes it is the process that is the
dominant partner and a material-mate must be found that is compatible with
it. It is a marriage. Compatibility is not easily found—many marriages fail—
and material failure can be catastrophic, with issues of liability and compensation. This sounds like food for lawyers, and sometimes it is: some specialists
make their living as expert witnesses in court cases involving failed materials.
But our aim here is not contention; rather, it is to give you a vision of the materials universe (since, even on the remotest planets you will find the same elements) and of the universe of processes, and to provide methods and tools for
choosing them to ensure a happy, durable union.
But, you may say, engineers have been making things out of materials for
centuries, and successfully so—think of Isambard Kingdom Brunel, Thomas
Telford, Gustave Eiffel, Henry Ford, Karl Benz and Gottlieb Daimler, the
Wright brothers. Why do we need new ways to choose them? A little history
helps here. Glance at the portrait with which this chapter starts: it shows James
Stuart, the first Professor of Engineering at Cambridge University from 1875 to
1890 (note the cigar). In his day the number of materials available to engineers
was small—a few hundred at most. There were no synthetic polymers—there
are now over 45 000 of them. There were no light alloys (aluminum was first
established as an engineering material only in the 20th century)—now there are
thousands. There were no high-performance composites—now there are hundreds of them. The history is developed further in Figure 1.1, the time-axis of
which spans 10 000 years. It shows roughly when each of the main classes of
materials first evolved. The time-scale is nonlinear—almost all the materials we
use today were developed in the last 100 years. And this number is enormous:
over 160 000 materials are available to today’s engineer, presenting us with a
problem that Professor Stuart did not have: that of optimally selecting from
this huge menu. With the ever-increasing drive for performance, economy and
efficiency, and the imperative to avoid damage to the environment, making the
right choice becomes very important. Innovative design means the imaginative
exploitation of the properties offered by materials.
These properties, today, are largely known and documented in handbooks;
one such—the ASM Materials Handbook—runs to 22 fat volumes, and it is one
of many. How are we to deal with this vast body of information? Fortunately
another thing has changed since Prof. Stuart’s day: we now have digital information storage and manipulation. Computer-aided design is now a standard part
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